Self-clearing liquid ballistic for gyro assembly



y 1961 w. R. KEYSER, JR 2,990,623

SELF-CLEARING LIQUID BALLISTIC FOR GYRO ASSEMBLY Filed Nov. 27, 1959INVENTOR WILL/AM KEYSER JR.

ATTORNEY 2 United States Patent 2,990,623 SELF-CIJEARING LIQUIDBALLISTIC FOR GYRO ASSEMBLY William R. Keyser, Jr., Charlottesville,Va., assignor to Sperry Rand Corporation, Great Neck, N.Y., acorporation of Delaware Filed Nov. 27, 1959, Ser. No. 855,568

' 3 Claims. c1. 33-226) The present invention relates to liquidballistic elements for gyro assemblies and, more particularly, to aself-clearing ballistic element which inhibits the formation of liquidglobule obstructions in the air tube of the ballistic.

As is well understood in the art, a liquid ballistic imparts a meridianseeking property to the directive element of a gyrocompass. Such aballistic is utilized in the gyrocompass disclosed, for instance, inPatent 2,887,- 784 issued on May 26, 1956, in the name of Leslie F.Carter and assigned to the present assignee. In the illustrative case ofthe patent, the ballistic comprises first and second liquid containerswhich are secured to the gyro rotor case at respective ends of the rotorspin axis. The containers are partially filled with a suitable liquidsuch as kerosene. The bottoms of the containers are connected to eachother by a small diameter tube to provide for the flow of liquid betweenthe containers. The tops of the containers are interconnected by abreather or air venting tube. v

Proper operation of the liquid ballistic, in imparting meridian seekingproperties to the gyro directive element, depends on the flow of liquidbetween the two containers of the ballistic. Any obstruction tending toblock such flow would seriously impair the meridian seeking action. Inparticular, it has been found' that under commonly encounteredconditions of'vibration, shock, or tilting ,of the liquid ballistic, amarked tendency exists for the formation of a liquid globule within theair tube interconnecting the ballistic containers. The droplet remainsin the region where the ends of the air tube flare into the tops of therespectively associated containers. The surface tension of the liquidprevents the droplet from falling out of the air tube and into thecontainer thereby blocking the tube.

It is the principal object of the present invention to provide aself-clearing liquid ballistic for use with gyroscope directive elementswhereby the formation of entrapped droplets within the ballistic airtube is inhibited.

Another object is to provide an improved liquid ballistic having airtube terminations arranged to shed liquid globules.

These and other objects of the invention, as will appear from a readingof the following specification, are accomplished in a preferredembodiment by the provision of a liquid ballistic element comprisingfirst and second liquid containers interconnected by air and liquidducts to provide a sealed system for the exchange of liquid between saidcontainers. The air duct interconnects the tops of the containers; theliquid duct interconnects the bottoms of the containers. The containersare preferably approximately half filled with a suitable liquid such as,for example, kerosene, when the ballistic element is in a neutralposition.

Each end of the air duct, where it enters into the top of itsrespectively associated container, is tapered so as to have a decreasingcross-sectional area. The tips of the tapered duct ends are submergedbeneath the level of the liquid within the containers when the ballisticelement is in its neutral position. Each tapered air duct end isapertured above the surface of the liquid to prowide for the freepassage of air between the two containers.

' containers contact the air duct termination as a result of, v

ice

In operation, should some of the liquid present in the for example,vibration, shock, or excessive tilting of the ballistic element, theliquid droplet so created in the duct termination will move toward thesubmerged end of the apertured and tapered air duct termination. Whenthe descending droplet comes into contact with the fluid of thecontainer, the droplet merges with said fluid thus completely clearingthe duct. In this manner the air duct interconnecting the liquidcontainers of the ballistic element is maintained. clear of liquidobstruction which otherwise would impair the proper meridian seekingoperation of the ballistic.

For a more complete understanding of the present invention, referenceshould be had to the following specification and to the appendedfigures, of which:

FIG. 1 is a perspective view of an illustrative liquid ballisticelement;

FIG. 2 is a sectional view of a representative prior art liquidballistic container showing the location of a droplet near the end ofthe air duct;

FIG. 3 is a sectional view of a liquid ballistic container modified inaccordance with the present invention; and

FIG. 4 is a sectional view of the apparatus of FIG. 3 taken along theline 4-4.

In FIG. 1, liquid ballistic element 1 is adapted by flanges 2 formounting on the directive element of a gyroscope (not shown). Element 1,for the sake ofillustration, is generally similar to the liquidballistic disclosed in Patent 2,887,784 and illustrated in FIGS. 3 and 7thereof. Element 1 comprises liquid containers 3 and 5 corresponding tocontainers 73 of the patent. Each of said containers is approximatelyhalf-filled with a suitable liquid 6 such as, for example, kerosene whenthe element is in the neutral position depicted in FIG. 1. the neutralposition, the liquid 6 also completely fills liquid-duct 7 whichinterconnects the bottoms of containers 3 and 5. Air duet 8interconnects the tops of containers 3 and 5 to provide for the freepassage of air between the containers. Thus, ducts 7 and 8 andcontainers 3 and 5 together comprise a sealed system partially filledwith a fluid 6 wherein provision is made for the free flow of fluid 6between containers 3 and 5 when the system is tilted from its neutralposition relative to horizontal axis 9.

It can be seen that in the event that the liquid ballistic of FIG. 1 issubjected to vibration or shock or is tilted appreciably with respect toaxis 9, the fiuid from the containers will come in contact with the endsof the air ducts at the tops of the containers. This is shown moreclearly in the view of FIG. 2. As the result of the surface tension ofthe fluid, droplet 10 will remain within tube 8 and will not fall intocontainer 3. It will be recognized that so long as droplet 10 remains atthe location shown, air and liquid flow between containers 3 and 5 issubstantially inhibited. The inevitable result is the loss of themeridian seeking properties afforded by the liquid ballistic. Droplet 10will continue to block the air duct 8 until it is blown out intocontainer 3 by increased air pressure within tube 8 behind droplet 10.

The formation of the droplet shown in FIG. 2 and the resultingundesirable operation of the liquid ballistic is prevented, inaccordance with the present invention, by suitable shaping of the endsof the air duct 8 in the region where they enter their respectivecontainers. In the preferred embodiment shown in FIG. 3, each end of airduct 8 has been modified to resemble the tip of a draftsmans pen. Theextremity 11 of each air duct termination extends below the level ofliquid 6 when the ballistic is in its neutral position relative tohorizontal axis 9 of FIG. 1. The slot 12 cut into each termination 11pro- 'vides for the normal venting of air through duct 8 to the 3containers of the ballistic. Slot 12 extends sufficiently above thesurface of liquid 6 for this purpose; The slotted termination 11 isfurther illustrated in the sectional view of FIG. 4 taken along the line4-4 of FIG. 3.

In operation, should a globule of liquid such as droplet 13 form at oneof' the duct terminations 11, the surface tension of the liquid willurge the droplet downwardly as indicated by the arrow toward thedecreasing crosssectional area portions of the tapered termination.Droplet 13 will continue its movement until it meets 'and merges withthe main body of the liquid 6 thereby completely clearing air duct 8.This action is self-maintaining whereby duct 8 is continuously clearedof droplets whenever they are produced.

It should be noted'that althoughthe tapered duct termination resemblesthe'tip of a draftsmans pen in the preferred embodiment, such a shape isnot uniquely necessary. All that is required is that each air duct endbe tapered toward a tip to have a reducing cross-sectional area.Additionally, the tip of the tapered duct termination must at leastcontact the surface of the liquid when the ballistic is in its neutralposition and the tapered termination must be apertured above the surfaceof the liquid for venting purposes.

While the invention has been described in its preferred embodiments, itis understood that the words which have been used are words ofdescription rather than of limitation and that changes within thepurview of the appended claims may be made without departing from thetrue scope and spirit of the invention in its broader aspects.

What is claimed is:

1. A self-clearing liquid ballistic comprising first and second closedcontainers, said containers being interconnected at one end by a ductpermitting the flow of:

liquid between said containers, said containers being interconnected atthe opposite end by a venting duct, said containers being partiallyfilled by a liquid, each end of said venting duct being tapered to havea decreasing crosssectional area toward a tip, said tip at eachend ofsaid venting duct penetrating the surface of said liquid, each taperedend being slotted longitudinally to provide forthe venting of airthrough said venting duct when said tip is submerged below the surfaceof said liquid.

2. A liquid ballistic for use in a gyrocompass, said ballisticcomprising first and second containers, said containers beinginterconnected at one end by a duct 'permitting the flow of liquidbetween said containers, said containers being interconnected at theopposite end by a venting duct, said containers being partially filledto the same level by a liquid when said ballistic is in a neutralposition, each end of said venting duct being tapered toward a, tip ofdecreased cross-sectional area, said tip at each end of said ventingduct penetrating the surface of said liquid when the ballistic is insaid neutral position, each tapered end being apertured above thesurface of said liquid.

3. A liquid ballistic for use in a gyrocompass, said ballisticcomprising first and second cylindrical containers adapted for mountingat respective ends of the gyro rotor spin axis, the bottoms of saidcontainers being in terconnected by a tube permitting the flow of liquidbetween said containers, the top ends of said containers beinginterconnected by a venting tube, said containers being partially filledto the same level by a liquid when said ballistic is in a horizontalposition, each end of said venting tube being tapered toward a tip ofdecreased cross-sectional area, said tip at each end of said ventingtube being submerged in said liquid when the ballistic is in saidhorizontal position, each tapered end being slotted above the surface ofsaid liquid.

References Cited in the file of this patent UNITED STATES PATENTS363,177 Sloppz May 17, 1887 1, 69,666 Wheeler June 18, 1918 1,777,958Brown Oct. 7, 1930v 1,970,883 Bryant Aug. 21, 1934 2,739,390 Carter Mar.27, 1956

